Many types of printers perform multiple printing passes over print media during the printing process. The print media is typically patterned with an ink pattern during each printing pass. In some cases, a new ink pattern is imprinted onto the same area of the print media that was previously imprinted upon during a prior printing pass. In some cases, a new ink pattern is imprinted onto an area of the print media immediately adjacent a print media area that was previously imprinted upon during a previous printing pass.
Some forms of print media often undergo distortion upon exposure to the moisture present in many printer inks. Examples of such print media distortion include, but are not limited to, expansion, cockling, and rippling. Other causes of print media distortion, expansion, cockling, and rippling include, but are not limited to, mechanical stresses such as for example stretching, twisting, binding, and thermal stresses. Print media distortion can lead to the misalignment of ink patterns imprinted onto the print media during the multiple printing passes.
Some prior art solutions seek to restrict print media distortion by securing the print media in place during a multi-pass printing process. Examples of print media securing mechanisms include tension based mechanisms and vacuum hold-down mechanisms. While such prior art solutions often reduce some forms of distortion, such as for example, expansion, in many cases, the print media releases stress induced by exposure to printer ink moisture in other forms of distortion, such as for example cockling or rippling. Furthermore, print media restriction mechanisms typically cannot be employed in situations where the printing assembly is maintained in a generally fixed position and the print media is moved with respect to the printing assembly during the multi-pass printing process.